“Sweet-spot” is a colloquialism used to describe a central area on a golf-club's face. A golf ball impacted by a properly aligned sweet-spot receives a maximum velocity and optimum trajectory. The same ball, if impacted by a misaligned club head, receives a lower velocity and is more likely to be misdirected. For these reasons, golf club manufacturers tend to design clubs in ways that maximize the sweet-spot's size. Although these efforts have proven effective, the goal of each golfer remains the same—to impact the golf ball at the sweet-spot. Failure to do so frequently produces misdirected shots of questionable duration.
By way of example, a golf ball impacted by the heel of a golf club swung by a right-handed golfer tends to “pull” to the left of the intended flight path. When impacted by the toe of the golfer's club, the same ball frequently tends to “pull” to the right of the intended trajectory. Even where neither of these mishaps occur, the ball often pursues a lower and shorter trajectory than if it had been hit by the sweet-spot.
Over the years, many efforts have been made to provide a means for a golfer to ascertain what area of the golf club face impacted the golf ball. After determining the point of impact and observing how much the point of impact deviates from the sweet-spot, the golfer makes whatever adjustments necessary to correct his or her swing, and tries again. U.S. Pat. No. 4,603,862 ('862 patent), U.S. Pat. No. 5,120,358 ('358 patent), U.S. Pat. No. 5,597,361 ('361 patent), U.S. Pat. No. 6,344,004 ('004 patent), and U.S. Pat. No. 6,585,604 ('604 patent) illustrate several approaches.
The '862 patent issued to Chen provides a golf ball that is permanently marked with a plurality of vertical and horizontal lines that may include special notations for yardage, a marking device comprising wooden block in which is formed recess or depression of hemispherical shape, and a chalked pad adhesively fixed to a golf club face. The golfer hits the golf ball and notes its flight. After retrieving the golf ball, the golfer determines the mark on the ball and calculates the impact point, e.g. the deviation from the sweet-spot. A disadvantage of this invention is that the ball must be retrieved before the point of impact can be determined.
The '358 patent issued to Pippett provides a flowable chalk compound, dispensed from a typical plastic squeeze tube. A dot of the flowable chalk compound is applied to one side of a conventional golf ball and the ball is positioned such that the face of a golf club will impact the ball at the dot of flowable chalk compound, which contains a hardening agent such as a gum that tends to dry or otherwise solidify when exposed to air. When the golf ball is struck by the face of a golf club at the dot of flowable chalk material, a mark forms on the club face at the point of impact. After the ball is hit, the golfer surveys the club face to determine whether the mark covers the sweet-spot. If not, the golfer adjusts his or her swing and tries again. A disadvantage of this invention is that a thick pasty residue is left on the club face from the flowable chalk compound. This residue must be wiped away with a cloth and can clog the grooves on the club face resulting in compromised ball action. Another disadvantage is that in order to apply the flowable chalk compound to a golf ball, both the ball and the dispenser must be handled simultaneously.
The '361 patent issued to Hope provides an adhesive backed appliqué which is affixed to the face of a golf club. When the club face is struck against a golf ball, the appliqué gives some indication of the strike point. A significant disadvantage, however, is that the appliqué covers the face of the club and thus obstructs the view of the club's actual sweet spot, which may be bigger or smaller than indicated by the appliqué. Another disadvantage of using an appliquéis that the club face itself never actually touches the ball. This can detrimentally affect the spin, and therefore the flight of the ball. Another disadvantage is that after five or six balls have been struck, the appliqué must be replaced because the marks on the appliqué left by previous ball strikes overlap and obscure locations of subsequent strikes.
The '004 patent issued to Adams provides a golf tee coated with colored coatings that when struck with a golf club leave a marking that easily identifies the point of impact. Specifically, the tee leaves a multicolored marking on the club face that is used to show the swing path of a golfer's swing and the point of impact of the tee on the face of the golf club. A disadvantage of this invention is that the face of a golf club may not impact the golf tee, and thus no indication of the point of impact would be given.
The '604 patent issued to Morrone provides an single piece of semi-stationary apparatus for golfers who want to exercise, self-teach, or teach the golf swing without actually sending a golf ball flying. Upon impact with the club face, the ball section of the apparatus ejects a material that marks the face of the golf club and shows the golfer where he or she hit the ball. A disadvantage is that this invention does not permit the hitting of conventional golf balls.